ringtest: commonize implementation of poll_avail/poll_used

Provide new primitives used_empty/avail_empty and
build poll_avail/poll_used on top of it.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

6 files changed, 43 insertions, 83 deletions

diff --git a/tools/virtio/ringtest/main.c b/tools/virtio/ringtest/main.c
index bda7f0dad981..b00ecd619969 100644
--- a/tools/virtio/ringtest/main.c
+++ b/tools/virtio/ringtest/main.c
@@ -96,6 +96,12 @@ void set_affinity(const char *arg)
         assert(!ret);
 }
 
+void poll_used(void)
+{
+        while (used_empty())
+                busy_wait();
+}
+
 static void __attribute__((__flatten__)) run_guest(void)
 {
         int completed_before;
@@ -149,6 +155,12 @@ static void __attribute__((__flatten__)) run_guest(void)
         }
 }
 
+void poll_avail(void)
+{
+        while (avail_empty())
+                busy_wait();
+}
+
 static void __attribute__((__flatten__)) run_host(void)
 {
         int completed_before;
diff --git a/tools/virtio/ringtest/main.h b/tools/virtio/ringtest/main.h
index 16917acb0ade..34e63cc4c572 100644
--- a/tools/virtio/ringtest/main.h
+++ b/tools/virtio/ringtest/main.h
@@ -56,15 +56,15 @@ void alloc_ring(void);
 int add_inbuf(unsigned, void *, void *);
 void *get_buf(unsigned *, void **);
 void disable_call();
+bool used_empty();
 bool enable_call();
 void kick_available();
-void poll_used();
 /* host side */
 void disable_kick();
+bool avail_empty();
 bool enable_kick();
 bool use_buf(unsigned *, void **);
 void call_used();
-void poll_avail();
 
 /* implemented by main */
 extern bool do_sleep;
diff --git a/tools/virtio/ringtest/noring.c b/tools/virtio/ringtest/noring.c
index eda2f4824130..b8d1c1daac7c 100644
--- a/tools/virtio/ringtest/noring.c
+++ b/tools/virtio/ringtest/noring.c
@@ -24,8 +24,9 @@ void *get_buf(unsigned *lenp, void **bufp)
         return "Buffer";
 }
 
-void poll_used(void)
+bool used_empty()
 {
+        return false;
 }
 
 void disable_call()
@@ -54,8 +55,9 @@ bool enable_kick()
         assert(0);
 }
 
-void poll_avail(void)
+bool avail_empty()
 {
+        return false;
 }
 
 bool use_buf(unsigned *lenp, void **bufp)
diff --git a/tools/virtio/ringtest/ptr_ring.c b/tools/virtio/ringtest/ptr_ring.c
index bd2ad1d3b7a9..635b07b4fdd3 100644
--- a/tools/virtio/ringtest/ptr_ring.c
+++ b/tools/virtio/ringtest/ptr_ring.c
@@ -133,18 +133,9 @@ void *get_buf(unsigned *lenp, void **bufp)
         return datap;
 }
 
-void poll_used(void)
+bool used_empty()
 {
-        void *b;
-
-        do {
-                if (tailcnt == headcnt || __ptr_ring_full(&array)) {
-                        b = NULL;
-                        barrier();
-                } else {
-                        b = "Buffer\n";
-                }
-        } while (!b);
+        return (tailcnt == headcnt || __ptr_ring_full(&array));
 }
 
 void disable_call()
@@ -173,14 +164,9 @@ bool enable_kick()
         assert(0);
 }
 
-void poll_avail(void)
+bool avail_empty()
 {
-        void *b;
-
-        do {
-                barrier();
-                b = __ptr_ring_peek(&array);
-        } while (!b);
+        return !__ptr_ring_peek(&array);
 }
 
 bool use_buf(unsigned *lenp, void **bufp)
diff --git a/tools/virtio/ringtest/ring.c b/tools/virtio/ringtest/ring.c
index c25c8d248b6b..747c5dd47be8 100644
--- a/tools/virtio/ringtest/ring.c
+++ b/tools/virtio/ringtest/ring.c
@@ -163,12 +163,11 @@ void *get_buf(unsigned *lenp, void **bufp)
         return datap;
 }
 
-void poll_used(void)
+bool used_empty()
 {
         unsigned head = (ring_size - 1) & guest.last_used_idx;
 
-        while (ring[head].flags & DESC_HW)
-                busy_wait();
+        return (ring[head].flags & DESC_HW);
 }
 
 void disable_call()
@@ -180,13 +179,11 @@ void disable_call()
 
 bool enable_call()
 {
-        unsigned head = (ring_size - 1) & guest.last_used_idx;
-
         event->call_index = guest.last_used_idx;
         /* Flush call index write */
         /* Barrier D (for pairing) */
         smp_mb();
-        return ring[head].flags & DESC_HW;
+        return used_empty();
 }
 
 void kick_available(void)
@@ -213,20 +210,17 @@ void disable_kick()
 
 bool enable_kick()
 {
-        unsigned head = (ring_size - 1) & host.used_idx;
-
         event->kick_index = host.used_idx;
         /* Barrier C (for pairing) */
         smp_mb();
-        return !(ring[head].flags & DESC_HW);
+        return avail_empty();
 }
 
-void poll_avail(void)
+bool avail_empty()
 {
         unsigned head = (ring_size - 1) & host.used_idx;
 
-        while (!(ring[head].flags & DESC_HW))
-                busy_wait();
+        return !(ring[head].flags & DESC_HW);
 }
 
 bool use_buf(unsigned *lenp, void **bufp)
diff --git a/tools/virtio/ringtest/virtio_ring_0_9.c b/tools/virtio/ringtest/virtio_ring_0_9.c
index 761866212aac..bbc3043b2fb1 100644
--- a/tools/virtio/ringtest/virtio_ring_0_9.c
+++ b/tools/virtio/ringtest/virtio_ring_0_9.c
@@ -194,24 +194,16 @@ void *get_buf(unsigned *lenp, void **bufp)
         return datap;
 }
 
-void poll_used(void)
+bool used_empty()
 {
+        unsigned short last_used_idx = guest.last_used_idx;
 #ifdef RING_POLL
-        unsigned head = (ring_size - 1) & guest.last_used_idx;
+        unsigned short head = last_used_idx & (ring_size - 1);
+        unsigned index = ring.used->ring[head].id;
 
-        for (;;) {
-                unsigned index = ring.used->ring[head].id;
-
-                if ((index ^ guest.last_used_idx ^ 0x8000) & ~(ring_size - 1))
-                        busy_wait();
-                else
-                        break;
-        }
+        return (index ^ last_used_idx ^ 0x8000) & ~(ring_size - 1);
 #else
-        unsigned head = guest.last_used_idx;
-
-        while (ring.used->idx == head)
-                busy_wait();
+        return ring.used->idx == last_used_idx;
 #endif
 }
 
@@ -224,22 +216,11 @@ void disable_call()
 
 bool enable_call()
 {
-        unsigned short last_used_idx;
-
-        vring_used_event(&ring) = (last_used_idx = guest.last_used_idx);
+        vring_used_event(&ring) = guest.last_used_idx;
         /* Flush call index write */
         /* Barrier D (for pairing) */
         smp_mb();
-#ifdef RING_POLL
-        {
-                unsigned short head = last_used_idx & (ring_size - 1);
-                unsigned index = ring.used->ring[head].id;
-
-                return (index ^ last_used_idx ^ 0x8000) & ~(ring_size - 1);
-        }
-#else
-        return ring.used->idx == last_used_idx;
-#endif
+        return used_empty();
 }
 
 void kick_available(void)
@@ -266,36 +247,21 @@ void disable_kick()
 
 bool enable_kick()
 {
-        unsigned head = host.used_idx;
-
-        vring_avail_event(&ring) = head;
+        vring_avail_event(&ring) = host.used_idx;
         /* Barrier C (for pairing) */
         smp_mb();
-#ifdef RING_POLL
-        {
-                unsigned index = ring.avail->ring[head & (ring_size - 1)];
-
-                return (index ^ head ^ 0x8000) & ~(ring_size - 1);
-        }
-#else
-        return head == ring.avail->idx;
-#endif
+        return avail_empty();
 }
 
-void poll_avail(void)
+bool avail_empty()
 {
         unsigned head = host.used_idx;
 #ifdef RING_POLL
-        for (;;) {
-                unsigned index = ring.avail->ring[head & (ring_size - 1)];
-                if ((index ^ head ^ 0x8000) & ~(ring_size - 1))
-                        busy_wait();
-                else
-                        break;
-        }
+        unsigned index = ring.avail->ring[head & (ring_size - 1)];
+
+        return ((index ^ head ^ 0x8000) & ~(ring_size - 1));
 #else
-        while (ring.avail->idx == head)
-                busy_wait();
+        return head == ring.avail->idx;
 #endif
 }